Chronic caffeine exposure reduces the excitant action of acetylcholine on cerebral cortical neurons.
Chronic administration of caffeine (s.c. for a period of 14 days in escalating doses of 10-70 mg/kg) decreased the sensitivity of rat cerebral cortical neurons to the excitant action of microiontophoretically applied acetylcholine. The sensitivity of spontaneously firing rat cerebral cortical neurons in caffeine-treated animals was compared with that of saline-treated controls using the same multiple barrel micropipettes tested on the same day. Acetylcholine sensitivity was determined by the E.T50 method. The E.T50 for 71 neurons in the caffeine-treated rats of 224.0 +/- 11.3 (S.E.M.) was significantly (P less than 0.001) greater than that of 65 neurons in the saline-treated control rats (153.8 +/- 6.9), indicating a reduction in the excitant action of acetylcholine on neurons which had been chronically exposed to caffeine. The level of spontaneous activity was also reduced in the caffeine-treated animals. A down-regulation of acetylcholine receptors is a possible cause for these effects.
Lin
Y
Y
Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201.
Phillis
J W
JW
D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D002800:Cholinesterase Inhibitors; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D002800:Cholinesterase Inhibitors; D002110:Caffeine; D000109:Acetylcholine